The name for the upcoming "Redstone 4" update of Windows 10, version 1803, today got revealed. It looks like Microsoft is keeping the "Creators Update" naming, using the wording "Windows 10 Spring Creators Update" as the full name of the OS.
The Spring Creators Update name has been spotted several times in various official announcements, but it wasn't confirmed officially by Microsoft. Recent research clearly shows that the name "Windows 10 Spring Creators Update" is now used in Microsoft's products as a reference to Windows 10 version 1803. See the following screenshot of Powershell on Windows 10 Build 17618 "Redstone 5".
This will be the third release of Windows 10 with the "Creators Update" naming scheme. The Creators Update family now includes:
Windows 10 version 1703 - Creators Update
Windows 10 version 1709 - Fall Creators Update
Windows 10 version 1803 - Spring Creators Update
The release of "Redstone 4", now known as Windows 10 Spring Creators Update, is expected for stable branch users in April 2018. A list of its key features can be found here:
Source: This twitter conversation